Medical plug-in connectors are used, for example, to connect a sphygmomanometer cuff to a blood pressure analysis unit in noninvasive blood pressure measurement applications.
A plug-in connector for pressure and vacuum tubes is known from U.S. Pat. No. 3,640,552. The prior-art connector has an inner plug-in part and an outer plug-in part, which extends around a front end area of the inner plug-in part in the attached state and is provided with protruding elastic snap-in hooks with radially inwardly protruding projections, which are bent at first radially outwardly when pushed over the inner plug-in part and then bring about a connection of the two plug-in parts with one another by snapping into corresponding depressions in the outer surface of the inner plug-in part. The elastic snapping in of the snap-in hooks with their protrusion in the depressions brings about axial fixation of the two plug-in parts in relation to one another. A circumferential sealing projection is provided in the interior of the passage as a freely protruding part of the inner plug-in part such that it comes into contact with a sealing projection in the inner passage of the outer plug-in part when the snap-in hook snaps in and establishes sealing by pressing on between the plug-in parts. The tubes to be connected by the plug-in connector are introduced each into the end of the plug-in part facing away from the connection area and fixed in the interior thereof, the tubes not reaching into the connection area of the two plug-in parts. Seals of complicated designs of each tube and the corresponding plug-in part and the two plug-in parts among each other are present.
A plug-in connector for medical tubes, which likewise has an inner plug-in part and an outer plug-in part, is known from EP 1 584 348 B1. At its end facing the connection area, the outer plug-in part has an inlet section designed as a hollow cylinder and a radially outwardly expanded, rounded holding section, which axially adjoins same and is designed for positive-locking meshing with an outwardly protruding holding section on the inner plug-in part. The holding section on the inner plug-in part is designed such that it can slide through the inlet section in the outer plug-in part when the plug-in parts are plugged into one another and separated while one or both plug-in parts undergo elastic deformation, after which it generates meshing with elastic positive-locking connection at the inner surface of the outer plug-in part after reaching the radially expanded holding section, as a result of which a holding function and a sealing function are brought about simultaneously by the holding sections meshing with one another. The tubes to be connected by the plug-in connector are always pushed from the outside onto connecting branches provided on the ends facing away from the connection area. As a result, another sealed connection must always be provided between the respective tube and the outer end of the plug-in part in the area of this connecting branch. This makes the design of the plug-in connector on the whole complicated, because tight connections must be established both between the tubes and the respective plug-in part and between the respective plug-in parts themselves. The central passage opening of the respective plug-in connectors has a different diameter, and the internal diameter is made larger especially in the coupling area compared to the area of the plug-in connectors that is located away from the coupling. Different diameters of the passage opening of the plug-in connectors may lead to attenuation of the measured signal and hence to an inaccurate measurement result during the transmission of the measured signal especially during a noninvasive blood pressure measurement.